For example, a liquid crystal panel used for a liquid crystal display device such as a liquid crystal television does not emit light, and thus a backlight unit is required as a separate lighting device. The backlight unit is known, which is arranged behind the liquid crystal panel (on aside opposite to a display surface side). The backlight unit includes a chassis having an opening on its surface side facing the liquid crystal panel, a light source housed in the chassis and an optical member (such as a diffuser sheet) provided in the opening of the chassis for effectively exit light emitted from the light source toward the liquid crystal side. light sources (for example, LEDs).
LEDs may be used for the light source and in such a case, an LED board on which the LEDs are mounted is housed in the chassis. The light emitted from the LEDs tends to have high directivity. Therefore, a diffuser lens may be provided for each LED to lower the directivity. The diffuser lenses are provided on the LED board. A backlight device including the LEDs and the diffuser lenses disclosed in Patent Document 1 has been known.    Patent Document 1: Japanese Unexamined Patent Publication No. 2008-304839